Actually, floating datum is still horizontal datum, but the datumelevation of different CMP is variable.
实际上浮动基准面还是水平基准面，只是不同CMP的水平基准面高程可以变化。
2
The transforming of survey datum and the control of axis, vertical level, elevation are of great importance on controlling quality of high-rise building construction.
在高层及超高层建筑工程中，测量基准传递和轴线、垂直度、高程控制是建筑物施工质量控制的重点内容之一。
3
The Beijing Fundamental Bench Mark (BFBM) is an important reference datum in the elevation control network in China.